Yiff in hell 

“Yiff in Hell” is a phrase used by those that oppose the furry fandom, directly aimed towards furries as a message to take the activities commonly associated with yiffing elsewhere

On 4chan, “Yiff in Hell” is typically found in Furry threads, used as a protest towards furries in an attempt to lower the amount of furry content posted on the site. While it has been seen spammed throughout threads in great numbers, certain self-identified furries have offered rebuttals stating that the argument doesn’t make sense

This is the proper meaning, rather then the "Other ones" trying to insult the Furry Fandom

Internet User: Yiff in hell furfag!
Furry: Does your swag raise money for charity?

Yiff in hell by Another Goddamn Furry June 6, 2015

yiff in hell furfag 

what people say to furries.
most commonly used by anti-furry groups.
Is seen as a deep insult to people who use it.

yIfF iN hEll fuRfaG.
Hurr hurr hurr fucking yiff in hell furfag.

yiff in hell furfag by Into gay truckers October 7, 2017

r/yiffinhell 

A subreddit (reddit forum) dedicated mainly to hating furries, and showing off questionable or unintentionally funny posts made by members of the furry fandom.

*As for most fandoms, it isn’t representitive of its entirety, but that didn’t stop most people from making cringe-focused communities...*

I’m not going to place an example because i would be misleading. Go look into r/yiffinhell yourself and don’t get on my back.

r/yiffinhell by flash_greenthing November 10, 2019